Hamster

Hamsters are small rodents that belong to the subfamily Cricetinae. This group contains 19 species, which are sorted into seven genera. Many hamsters have become popular small pets.

The best-known hamster is the golden or Syrian hamster (Mesocricetus auratus). It is the type most often kept as a pet. Other hamsters kept as pets include three kinds of dwarf hamster: Campbell's dwarf hamster (Phodopus campbelli), the winter white dwarf hamster (Phodopus sungorus), and the Roborovski hamster (Phodopus roborovskii). The Chinese hamster (Cricetulus griseus) is also kept as a pet, though it is less common.

Hamsters eat mostly seeds, fruits, and plants, and sometimes they eat burrowing insects. In the wild, they are crepuscular, which means they search for food during twilight hours. In captivity, however, they are known to follow a typical nocturnal pattern, waking around sundown to eat and exercise.

Hamsters have stout bodies with several easy-to-spot features. Their cheek pouches are long and stretch all the way to their shoulders. They use these pouches to carry food back to their burrows. Hamsters also have a short tail and feet covered in fur.

Classification

Further information: List of cricetines

Hamsters belong to the subfamily Cricetinae, which is part of the larger family Cricetidae. This family also includes voles, lemmings and muskrats (all of which are in Arvicolinae), and New World rats and mice (Neotominae, Sigmodontinae and Tylomyinae). Within Cricetidae, hamsters are most closely related to Arvicolinae. Cricetidae is part of the larger group Muroidea, and it is most closely related to Muridae. Muridae includes Murinae (the Old World rats and mice) and gerbils (Gerbillinae), among others.

The earliest hamsters appeared during the Middle Miocene, around 15 million years ago. The group most likely began in central or eastern Europe and reached eastern Asia by around 10 million years ago. A 2026 analysis found that the ancestor of all living hamsters probably lived around 5-6 million years ago, at the end of the Miocene, probably somewhere around southeast Europe or West Asia.

Etymology

The name "hamster" is a loanword from German. It comes from an earlier Middle High German word, hamastra. It may be related to the Old Church Slavonic word khomestoru. That word may mix the root of the Russian word хомяк (khomyak), meaning "hamster," with a Baltic word such as Lithuanian staras, also meaning "hamster." It may instead come from Persian, like the Avestan word hamaēstar, meaning "oppressor."

A group of hamsters is called a "horde." In German, the verb hamstern comes from Hamster and means "to hoard."

Hamsters are stout-bodied, with short tails, small furry ears, short stocky legs, and wide feet. Their thick, silky fur can be long or short and can be black, grey, honey, white, brown, yellow, red, or a mix, depending on the species. Two species in the genus Phodopus, Campbell's dwarf hamster (P. campbelli) and the Djungarian hamster (P. sungorus), and two in the genus Cricetulus, the Chinese striped hamster (C. barabensis) and the Chinese hamster (C. griseus), have a dark stripe running from their heads to their tails. The Phodopus species are the smallest, with bodies 5.5 to 10.5 cm (2.2 to 4.1 in) long. The largest is the European hamster (Cricetus cricetus), which measures up to 34 cm (13 in) long, not including a short tail of up to 6 cm (2.4 in). Most hamster tails are hard to see because they are only about 1⁄6 the length of the body, but the Chinese hamster has a tail as long as its body. Hamsters have sharp incisors that keep growing, so they must be worn down regularly. They are very flexible, but their bones are somewhat fragile, and they are very sensitive to rapid temperature changes, drafts, and extreme heat or cold.

Hamsters have poor eyesight. They are nearsighted and colorblind, so they do not have a good sense of distance, but this does not stop them from climbing in and out of their cages or from being adventurous. They can sense movement all around them at all times, which helps protect them from harm in the wild. Hamsters have scent glands on their flanks (and on their bellies in Chinese and dwarf hamsters), which they use to leave a scent trail and mark their territories, babies, or mate. They also use smell to tell the sexes apart, to find food, and mothers use it to find their own babies. Their ears stand upright to catch sounds, and they are sensitive to high-pitched noises, hearing and communicating in the ultrasonic range. Hamsters are omnivores, so they can eat both meat and plants. Wild hamsters eat seeds, grass, and insects, while pet hamsters can survive on commercial hamster food alone, though vegetables, fruits, seeds, and nuts can also be given. Hamsters are hindgut fermenters and often eat their own feces (coprophagy) to recover nutrients that were digested in the hind gut but not absorbed.

Behavior

Hamsters are known for food hoarding. They carry food in their cheek pouches to underground storage chambers, and their cheeks can make their heads look two or three times bigger when full. Hamsters lose weight in autumn to prepare for winter, even when kept as pets. Most hamsters live alone. If they are kept together, they may have stress and may fight fiercely, sometimes fatally. Dwarf hamsters might get along with siblings or unrelated hamsters of the same sex if they are introduced at a young enough age, but this cannot be guaranteed. Hamsters communicate with each other and with their owners through body language and by giving off a specific scent from their scent glands.

Hamsters can be described as nocturnal or crepuscular, meaning they are active mostly at dawn and dusk. Some writers call them nocturnal, while others note that they spend most of the day underground and leave their burrows about an hour before sundown, so they are mainly crepuscular. In the wild, Syrian hamsters can hibernate, letting their body temperature fall close to the temperature around them. This thermoregulation lowers their metabolic rate to about 5% and helps them need much less food in winter. Hibernation usually lasts 2–3 days, though it can last up to a week. Syrian hamsters kept as house pets do not hibernate. All hamsters are excellent diggers, building burrows with entrances, tunnels, and chambers for nesting and storing food. In the wild, burrows protect them from extreme temperatures and predators. Wild hamsters may also use tunnels made by other mammals; the Djungarian hamster, for instance, uses paths and burrows of the pika.

Reproduction

Hamsters become fertile at different ages depending on their species. Syrian and Russian hamsters can start having young at only 4–5 weeks old. Chinese hamsters usually start at two to three months, and Roborovski hamsters at three to four months. A female's reproductive life lasts about 18 months, but males stay fertile much longer. Females are in estrus about every four days. During this time, their genital areas turn reddish, they have a musky smell, and they hiss and squeak if they think a male is nearby. A ready-to-breed female has a trim tail line when seen from above, while a male's tail line bulges on both sides. Male hamsters have very large testes for their body size.

Syrian hamsters are seasonal breeders and can have several litters a year, usually from April to October in the Northern Hemisphere. Their litters average about seven pups but can reach 24. Dwarf hamsters breed all year. Campbell's dwarf hamsters usually have four to eight pups, and up to 13. Hamsters are born hairless and blind in a nest their mother prepares in advance, and they begin exploring after about a week. Hamsters can be bred after they are three weeks old. Females can be aggressive toward males if they are kept together too long after mating, so the pair should be separated. A mother may cannibalize her litter if she feels threatened or if she is kept with them for three weeks or more, so the young must be removed once they can feed and drink on their own. Syrian hamsters usually live two to three years in captivity, and Russian hamsters about two to four years.

Society and culture

The Syrian hamster or golden hamster (Mesocricetus auratus) was first described scientifically by George Robert Waterhouse in 1839. Researchers could not successfully breed and keep hamsters as domestic animals until 1939. Nearly all lab and pet Syrian hamsters seem to come from one brother and sister pair, which Israel Aharoni, a zoologist of the University of Jerusalem, brought from Aleppo in Syria in 1930. Their descendants were later sent to the United States, where Syrian hamsters became common pets and lab animals. The golden hamster is the best-known species and the one most often kept as pets. It has many Syrian hamster variations, including long-haired types and different colors.

Other hamsters often kept as pets are the three species in the genus Phodopus. Campbell's dwarf hamster (Phodopus campbelli) is the most common. The winter white dwarf hamster (Phodopus sungorus) turns almost white in winter, and the Roborovski hamster (Phodopus roborovskii) is so small and fast that it is hard to keep as a pet. A hamster show is an event where people gather hamsters to judge them against each other, and it is also a place where hamster fans share their enthusiasm. Judging usually aims to promote hamsters that match natural or established types, which encourages careful breeding. When the first reported case of animal-to-human transmission of SARS-CoV-2 in Hong Kong involved imported pet hamsters, researchers had difficulty identifying some viral changes in a global genomic data bank. City authorities then announced a mass cull of hamsters bought after 22 December 2021, affecting about 2,000 animals. About 3,000 people joined secret efforts to adopt abandoned hamsters and keep pets, and the government later warned that some of these activities would face police action. Hamsters are also used in research, where cells from babies' kidneys and adults' ovaries help scientists study cholesterol synthesis.

Similar animals

Some rodents are sometimes called "hamsters" even though they are not in the hamster group Cricetinae. One example is the maned hamster, also called the crested hamster, which is really the maned rat (Lophiomys imhausi). Other examples are the mouse-like hamsters (Calomyscus spp.) and the white-tailed rat (Mystromys albicaudatus).